This invention relates to olefin polymerization and more particularly relates to deactivation of catalyst residues contained in propylene polymers.
Crystalline propylene polymers and their methods of manufacture are well known in the art. Propylene polymers are produced commercially using a transition metal compound/aluminum alkyl catalyst system. However, in such propylene polymer production, catalyst residues must either be removed or deactivated prior to practical use in order to avoid polymer corrosivity in undeactivated or "live" polymer.
Live polymer deactivation especially is critical to polymer produced in bulk and gas-phase polymerization processes where catalyst residues typically are not removed from the polymer in contrast to polymer produced in a slurry process.
Many polymer deactivation methods have been disclosed including treatment with water, caustic, alcohols, oxygen and alkylene oxides.
Examples of such methods are found in U.S. Pat. Nos. 2,838,477, 2,918,461, 3,110,708, 3,436,386, 3,318,857, 3,496,156, 3,502,633, 3,377,332, 4,029,877, 4,156,075, 4,167,619, 4,182,852, 4,195,145 and 4,197,398; British Pat. Nos. 1,272,778 and 1,091,644; and Japanese Published Application Nos. 139,833/75 and 126,291/79. U.S. Pat. No. 3,435,019 describes the use of aqueous ammonia and amine compounds in an extruder to deactivate catalyst residues. Japanese Published Application No. 18,422/80 discloses adding ammonia to a polyolefin to deactivate catalyst residues. U.S. Pat. No. 2,921,057 discloses use of anhydrous ammonia and butanol for catalyst residue deactivation. British Pat. No. 1,420,837 describes a process to reduce halogen content in a polyolefin by reacting the polyolefin in a fluid bed with nitrogen, steam and an alkylene oxide. Although many deactivation methods have been disclosed, there is a need for an effective catalyst deactivation method which can be used in a dry environment, especially for use with polymer produced from gas-phase or bulk polymerization processes.